Typically, a vibration-based angular rate sensor includes a sensing element that has a vibrating member and detects an angular rate based on a vibration of the vibrating member. The sensing element is fixed to a base such as a circuit board or a case through a wiring member.
The vibrating member is forced to vibrate normally in a predetermined direction. When the vibrating member is rotated, the vibrating member is subjected to coriolis forces. The coriolis forces cause a secondary vibration in a different direction from that of the original vibration. By sensing the secondary vibration, the angular rate can be detected. The two (i.e., original and secondary) vibrations are generally of high frequency of several thousand hertz (Hz).
The angular rate sensor has a vibration isolator that reduces a structural resonance frequency of the sensing element in order to prevent the structural resonance frequency from being equal to the secondary vibration frequency. For example, the structural resonance frequency is reduced to a value ranging from tens to several hundred Hz.
In a vibration-based angular rate sensor disclosed in U.S. Pat. No. 6,880,399, a metal lead wire shaped like a spring is used as the wiring member. Due to the spring-like shape, the lead wire acts as the vibration insulator. In this case, the lead wire needs to have flexibility enough to reduce the structural resonance frequency. The flexibility may be increased by increasing the length of the lead wire. However, an increase in the length of the lead wire may increase the size of the sensor and reduce mechanical strength of the lead wire. Therefore, the sensor may have large size and low reliability.